What is allergy skin testing?

Allergy skin testing helps diagnose allergies. Allergy skin testing can identify 10 to 50 specific substances, called allergens, which cause allergy symptoms in children and adults. Common allergens include foods, latex, medications, insect stings, and environmental particles, such as dust, pollen and mold.

An allergist will interpret your allergy skin testing results in relation to your medical history, physical exam, and other tests. An allergist, also known as an allergist-immunologist, has the specialized skills and experience needed to read allergy skin testing results properly. 

Allergy skin testing is only one method used to diagnose allergies. You may have less invasive testing options. Consider getting a second opinion about all of your testing choices before having allergy skin testing. 

Types of allergy skin testing

The types of allergy skin testing include:

  • Prick/puncture/scratch skin test involves applying a diluted allergen with a small prick, puncture, or scratch to the skin’s surface. 
  • Intradermal test involves injecting a diluted allergen below the skin surface using a tiny needle. Doctors sometimes use intradermal tests after a negative scratch skin test to collect more information about possible allergens.

Other procedures that may be performed

Your doctor may combine allergy skin testing with the following tests and procedures to diagnose allergies:

  • Allergy symptom log to record when you have symptoms, how long they last, what you were doing at the time, what medications you took, and how the medication worked. 
  • Elimination diet to eliminate certain foods one by one to see if certain foods cause allergy symptoms
  • Food log to record the foods you eat and if they cause allergy symptoms
  • RAST (radioallergosorbent test), a blood test to help identify the substances that cause your symptoms

Why is allergy skin testing used? 

Your doctor may recommend allergy skin testing to diagnose the cause of allergy symptoms from the following types of allergens:

  • Environmental allergens including mold, dust mites, pet dander, or tree pollen 
  • Food allergens including peanuts, milk, wheat and eggs
  • Insect venom 
  • Latex
  • Medications including penicillin 

Ask your doctor about all of your testing options and consider getting a second opinion before deciding on allergy skin testing.

Who performs allergy skin testing?

An allergist or pediatric allergist performs or supervises allergy skin testing.  Sometimes, a specially trained registered nurse (RN) performs the testing. 

Allergists, also known as allergist-immunologists, specialize in caring for people with allergies, asthma, and other diseases of the immune system. Pediatric allergists specialize in caring for children from infancy though adolescence with the same diseases and conditions. Allergists have advanced training and education to read allergy skin tests properly.

How is allergy skin testing performed?

Your allergy skin testing will be performed in a doctor’s office or clinic. A prick/puncture/scratch skin test tests for 10 to 50 allergens. It generally involves these steps:

  1. Your doctor completes a medical history and physical exam and asks you about your allergy symptoms.
  2. You may keep an allergy log to help determine the most likely allergens. A log can include recording when you have symptoms, how long they last, what you were doing at the time, what medications you took, and how the medication worked.
  3. You may participate in an elimination diet if your doctor suspects food allergies. This diet eliminates foods one by one to see if a certain food causes symptoms. Your doctor will evaluate the above steps to decide if you are a good candidate for allergy skin testing. 
  4. Your doctor will also ensure that allergy skin testing does not put you at risk for a serious reaction, such as anaphylaxis or an asthma attack.
  5. Your doctor or nurse will apply the allergens with a tiny prick or scratch on the surface of your skin. The forearm is the usual site in adults. The back is the usual site in children. This process takes five to 10 minutes.
  6. Your doctor will examine your skin after about 15 to 20 minutes. You may be allergic to a particular allergen if a small red lump appears at any of the allergen prick or scratch sites on your skin. 
  7. Your doctor will interpret the results in relation to your medical history, physical exam, and other tests.